Described herein is a process for producing a propylene copolymer in at least a pre-polymerization stage, a first and a second reaction stage connected in series with improved monomer recovery, wherein a product stream, comprising a propylene polymer mixture, unreacted propylene, unreacted ethylene and hydrogen, if present, is separated in a separation unit into a first overhead stream and a first bottom product stream, wherein the desired propylene polymer mixture is recovered from the first bottom product stream. The first overhead stream is at least partially condensed, passed to a distillation column and separated into a second overhead stream and a second bottom product stream. The second overhead stream is at least partially condensed and split into three distinct streams, wherein a distillation reflux stream is returned into the distillation column, a first recycle stream is passed to the second reaction stage and a second recycle stream is passed to a stripping column from where a third bottom product stream is withdrawn and at least a part of it is passed to a propylene feed vessel, to the pre-polymerisation stage, to the first reaction stage, or to a combination thereof. Further disclosed is a polymerization unit, particularly suitable for carrying out the inventive process.

A (meth)acrylic resin composition is obtained by a method comprising: continuously feeding a raw material solution essentially comprising methyl methacrylate, a chain transfer agent and a radical polymerization initiator, and optionally comprising an acrylic acid alkyl ester in a mass ratio of the acrylic acid alkyl ester to the methyl methacrylate of 0/100 to 20/80 into a tank reactor to allow bulk polymerization to proceed in the tank reactor at a polymerization conversion ratio of 40 to 70% by mass to obtain a reaction product while continuously discharging the reaction product from the tank reactor; heating the discharged reaction product with a heat exchanger; removing volatile matter from the heated reaction product; filtrating a liquid additive through a filter; and adding the filtrated liquid additive to the reaction product from which the volatile matter has been removed.

A (meth)acrylic resin composition is obtained by a method comprising: continuously feeding a raw material solution essentially comprising methyl methacrylate, a chain transfer agent and a radical polymerization initiator, and optionally comprising an acrylic acid alkyl ester in a mass ratio of the acrylic acid alkyl ester to the methyl methacrylate of 0/100 to 20/80 into a tank reactor to allow bulk polymerization to proceed in the tank reactor at a polymerization conversion ratio of 40 to 70% by mass to obtain a reaction product while continuously discharging the reaction product from the tank reactor; heating the discharged reaction product with a heat exchanger; removing volatile matter from the heated reaction product; filtrating a liquid additive through a filter; and adding the filtrated liquid additive to the reaction product from which the volatile matter has been removed.

A method of removing VOCs from a molten polymer comprising: (a) polymerizing monomers in a reactor to produce a reaction mixture comprising unreacted monomers and molten polymer, (b) removing a portion of unreacted monomers from at least a portion of the reaction mixture to produce recovered monomers and degassed molten polymer, wherein the degassed molten polymer comprises VOCs, (c) contacting at least a portion of the degassed molten polymer with an inert stripping agent at a pressure equal to or greater than atmospheric pressure to produce stripped molten polymer and spent stripping agent, wherein the inert stripping agent is insoluble in the degassed molten polymer, and wherein the spent stripping agent comprises at least a portion of the inert stripping agent and at least a portion of the VOCs from the degassed molten polymer, and (d) cooling at least a portion of the stripped molten polymer and forming polymer pellets.

A method of removing VOCs from a molten polymer comprising: (a) polymerizing monomers in a reactor to produce a reaction mixture comprising unreacted monomers and molten polymer, (b) removing a portion of unreacted monomers from at least a portion of the reaction mixture to produce recovered monomers and degassed molten polymer, wherein the degassed molten polymer comprises VOCs, (c) contacting at least a portion of the degassed molten polymer with an inert stripping agent at a pressure equal to or greater than atmospheric pressure to produce stripped molten polymer and spent stripping agent, wherein the inert stripping agent is insoluble in the degassed molten polymer, and wherein the spent stripping agent comprises at least a portion of the inert stripping agent and at least a portion of the VOCs from the degassed molten polymer, and (d) cooling at least a portion of the stripped molten polymer and forming polymer pellets.

Disclosed are insert assemblies with stacked gas flow gaps to add and/or remove gases from a solid/gas mixture travelling through a barrier. An example system may comprise a barrier and an insert assembly in the barrier defining an annulus between the insert assembly and the barrier, wherein the insert assembly comprises stacked flow gaps configured for addition and/or removal of gas from a solid/gas mixture flowing in the annulus.

A polypropylene composition comprising oligomers having a semi-volatile organic condensable (FOG,VDA 278 October 2011), content of 50 μg/g to about 400 μg/g of the total polypropylene composition, and volatile organic compounds (VOC,VDA 278 October 2011) in an amount of less than 80 μg/g of the total polypropylene composition, wherein the weight ratio of said oligomers versus said volatiles is more than about 5.0, wherein the polypropylene composition has an MFR.sub.2 (ISO 1133, 230° C., 2.16 kg) of 10 g/10 min or higher, wherein the polypropylene composition a flexural modulus (ISO 178 on injection moulded specimens of 80×10×4 mm prepared in accordance with ISO 294-1:1996) of from 1000 to 2000 MPa, and wherein the total quantity of slip agent is at least 500 ppm.

A polypropylene composition comprising oligomers having a semi-volatile organic condensable (FOG,VDA 278 October 2011), content of 50 μg/g to about 400 μg/g of the total polypropylene composition, and volatile organic compounds (VOC,VDA 278 October 2011) in an amount of less than 80 μg/g of the total polypropylene composition, wherein the weight ratio of said oligomers versus said volatiles is more than about 5.0, wherein the polypropylene composition has an MFR.sub.2 (ISO 1133, 230° C., 2.16 kg) of 10 g/10 min or higher, wherein the polypropylene composition a flexural modulus (ISO 178 on injection moulded specimens of 80×10×4 mm prepared in accordance with ISO 294-1:1996) of from 1000 to 2000 MPa, and wherein the total quantity of slip agent is at least 500 ppm.

A method for the removal of unreacted olefin monomer(s) from polyolefin product particles of an olefin polymerization reaction, the method including: contacting the polyolefin product particles with a countercurrent flow of a purge gas in a purge vessel under conditions allowing diffusion of unreacted monomer and other gaseous substances from the polyolefin product particles into the countercurrent flow of the purge gas to produce purged particles; wherein the velocity of the purge gas exceeds 50% of the calculated minimum fluidization velocity of the polyolefin product particles in the purge vessel (U.sub.mf), is provided.

A method for the removal of unreacted olefin monomer(s) from polyolefin product particles of an olefin polymerization reaction, the method including: contacting the polyolefin product particles with a countercurrent flow of a purge gas in a purge vessel under conditions allowing diffusion of unreacted monomer and other gaseous substances from the polyolefin product particles into the countercurrent flow of the purge gas to produce purged particles; wherein the velocity of the purge gas exceeds 50% of the calculated minimum fluidization velocity of the polyolefin product particles in the purge vessel (U.sub.mf), is provided.